It looks like this campaign isn't going to be funded but I thought I'd mention while there was still time to back it.

The Hatalogico is a relatively simple hat which adds 16 channels of hardware PWM and 8 channels of ADC to a Raspberry Pi.

I think the guy running the Kickstarter is honest but I'm still undecided about fully recommending the board. It seems like an easy way to add PWM and ADC to a Pi.

John is sending me a board to review but it will likely arrive after the Kickstarter campaign ends.

In case any of you are unaware, Parallax is selling a Propeller based hat.

Discussion here:

Bill Henning sells a nice "hat" which includes a Propeller, EEPROM and ADC. I don't think Bill's board is technically a hat since it came out before the hat specification was announced (I think).